Lawn mowers are known in the art. For example, stand-on mowers are discussed in U.S. Pat. Nos. 6,138,446, 6,390,225, 6,189,304, 6,438,930, 6,658,831, 6,560,952, 7,428,884 and 5,964,082, the disclosures of all of which are all hereby incorporated herein by reference. Example walk-behind lawn mowers are discussed in U.S. Patent Documents 2005/0126146 and 4,920,733, the disclosures of which are all hereby incorporated herein by reference. Example mower operable by seated occupants are discussed in U.S. Patent Documents 2001/0001170, 2002/0059788, U.S. Pat. Nos. 6,438,930, 6,658,831, and 6,560,952, the disclosures of which are all hereby incorporated herein by reference.
Traditionally mower deck lift systems sometimes include a handle or foot lever to raise or lower the cutter deck assembly. A selector or a stop pin are commonly used to control height of the cutter deck assembly and thus the height at which the mower cuts grass. There may also be a slackening connection in the deck lift system such as a chain or a slotted linkage for allowing the deck to float/raise over uneven contours in the ground. A bias, such as a spring, is commonly used to assist the operator in changing cut heights. However, providing too great of a spring bias has been thought to be undesirable in the art because it incurs problems where the deck will bounce upward when mowing over uneven ground thereby causing uneven grass cutting. Thus, those skilled in the art have conventionally avoided using too much spring bias in connection with deck lift systems.
Contrary to the longstanding belief in the art that too much spring force is undesirable in a deck lift system with a floating deck, example embodiments of this invention overspring/overbias the deck lift system. “Overspringing” and “overbiasing” the deck lift system, as used herein, means that the spring(s) provided in the deck lift system is/are capable of lifting more weight than the weight of what is lifted/lowered by the deck lift system in at least part of the range of movement of the deck lift system. Thus, the spring(s) in the deck lift system are capable of lifting more than 100% of the weight of what the deck lift system lifts (including the cutter deck) during at least part of the range of movement of the cutter deck. Example embodiments of the invention overcome the problem of the floating cutter deck bouncing upwardly too much during mower operations over uneven ground and thus causing uneven grass cutting by providing an incremental selector system that selectively and substantially locks the floating cutter deck against upward movement during mowing operations so as to restrain/reduce cutter deck bouncing. In example embodiments of this invention, the bias (spring(s)) is/are integrated into the incremental selector deck lift system so as to limit the bias applied to raising at least the cutter deck until a selector is disengaged. The spring(s) may be located in the deck lift system so as to work against linkage of the deck lift system, as opposed to working directly against the cutter deck. In certain example embodiments of this invention, when the selector is disengaged, an operator has to physically push down on the deck lift lever in order to lower the cutter deck in at least some of the movement range of the deck lift system (this may be the case throughout the entire range of movement in the cutter deck system; or in only part of the range of movement in the cutter deck system over which the cutter deck moves and in such cases in the remaining part of the range of movement in the cutter deck system the cutter deck lowers when the selector is disengaged without the operator having to physically push down on the deck lift lever). In certain example embodiments of this invention, when the selector is disengaged, an operator has to physically push down on the deck lift lever in order to lower the cutter deck in at least 10% of the cutter deck movement range of the deck lift system, more preferably in at least 20% of the cutter deck movement range of the deck lift system, even more preferably in at least 40% of the cutter deck movement range of the deck lift system, and sometimes in at least 50% of the cutter deck movement range of the deck lift system. The greater the overspringing amount is over 100% of what the deck lift system lifts, the greater the percentage of the deck lift system movement range where an operator has to physically push down on the deck lift lever in order to lower the cutter deck.
In certain example embodiments of this invention, the deck lift lever for lifting and lowering at least the cutter deck can be designed so as to communicate with one or more pivoting lift assemblies for the purpose of raising/lowering at least the cutter deck. The selector may be integral to the lever or separate from the lever. A technical advantage is that the bias can be increased significantly without incurring significant deck bounce even to the extent that the bias can be greater than force/weight of what is lifted and lowered by the deck lift system thereby allowing an operator of the mower to more easily raise and lower at least the cutter deck. This is particularly beneficial on large heavy commercial mowers and significantly less costly and more reliable than using solely electric or hydraulic power for raising and lowering the cutter deck. Advantages of this invention are applicable to mowers where the operator is standing on the mower or walking behind the mower where it's more problematic to use foot actuated deck lifts, but are also applicable to mowers where the operator is sitting on the mower during operation and moving the cutter deck with a hand lever or foot lever.
In certain example embodiments of this invention, the deck lift system is for selectively raising and lowering the cutter deck, engine deck, and engine as one unit. Thus, in such embodiments where the combination of the cutter deck assembly, engine deck assembly and engine are lifted/lowered together by the deck lift system, “overspringing” and “overbiasing” the deck lift system means that the spring(s) provided in the deck lift system is/are capable of lifting the combination of the cutter deck assembly, engine deck assembly and engine in at least part of the range of movement of the deck lift system.
In certain example embodiments of this invention, the mower includes: independently controlled right and left rear drive wheels (e.g., a zero turning radius mower); a cutter deck assembly including at least two grass cutting blades; a mower frame supporting at least the cutter deck assembly; at least one pivoting lift assembly linked to at least the cutter deck assembly to help raise and/or lower the cutter deck assembly; a slackening connection (e.g., one or more chains) allowing at least the cutter deck assembly to float relative to the frame; a lever with an incremental selector either integral to the pivoting assembly or linked to the pivoting assembly; and at least one biasing member (e.g., spring) assisting the pivoting assembly in raising the cutter deck and for overspringing/overbiasing the deck lift system.